1. Field of the Invention
The present invention relates generally to an improved method for irradiating a specimen by corpuscular-beam radiation.
2. Description of the Prior Art
Methods for irradiating a specimen by corpuscular-beam radiation in the form of a surface pattern having areas unexposed to the beam which are surrounded at least almost completely by areas exposed to the beam and in which a mask having a pattern corresponding to the surface pattern to be generated and a support grid comprising a plurality of parallel strips which support the areas of the mask corresponding to the unexposed areas of the surface pattern are uniformly illuminated by a corpuscular beam, and in which the image of the mask is optically shifted at least approximately perpendicular to the strips of the support grid by a distance which is at least equal to the width of the strips, are known in the art. Such a method is described in pending patent application Ser. No. 617,062, filed on Sept. 26, 1975 entitled "Improved Charged Particle Beam Optical Appartus for Irradiating a Specimen in a Two Dimensional Pattern" now U.S. Pat. No. 4,021,674.
In the known method, the problem of causing the image of the support grid to disappear is solved. In order to achieve this, the image of the mask is intermittently deflected by a deflection system located behind the mask along the beam path.